Introduction & Test Method

If you take a look through the CPU Cooler Reviews section of The Tech Buyer's Guru, you'll see we've tested quite a few models over the years. In fact, in all, we've had our hands on over two dozen coolers, of all shapes, sizes, and price classes. But one area we haven't spent quite as much time on is liquid coolers. It's not that we haven't tested them - in fact, the original Corsair Hydro H100i showed up in our comprehensive Complete Guide to CPU Coolers published in May 2015, which served as an introduction to the full range of CPU coolers on the market, and we returned to the subject with a review of the Corsair Hydro H100i v2 in early 2016. At that time, Corsair had a near lock on the "All-in-One" (AIO) market, and the H100i v2 has been the best selling liquid cooler ever since.

But nothing stands still in technology, and just as you typically shouldn't buy a CPU, video card, or SSD released two or three years ago, older CPU coolers should be viewed with a critical eye. Sometimes old doesn't mean "best," even if it is a best-seller. It may just mean that the word hasn't got out that old means old! In the past few years, a huge number of liquid coolers have hit the market, along with several new AMD and Intel CPU sockets. So we decided it was the right time for a full liquid cooler shootout. The one requirement: the cooler had to be a new model, and it had to include an AMD AM4 bracket right in the box so that Ryzen CPUs were supported. That excluded Corsair entirely, which actually hasn't shipped a new cooler in two years, and may be exiting the market, based on our analysis of its product showcases at CES and PAX over the past few years (where coolers often haven't even appeared). We'll actually circle back to the H100i v2 we have on hand to discuss it at the end of this article, but suffice it to say that it has been thoroughly out-classed by newer designs, and will soon be "existing stage right" from all of our buyer's guides.

Luckily, over the past few years, we've developed enough of a reputation and rapport with all the biggest CPU cooler manufacturers that when we come calling, they always answer. This time around we've got Arctic, CoolerMaster, Reeven, and Thermaltake lined up for the event. Here's a photo of the four coolers we're testing, followed by their retail prices as of our publication date:

As a baseline reference model, we're also testing Noctua's NH-D15 SE-AM4, the best air cooler on the market. It's a special AM4-only model, but the NH-D15 can also be found with standard Intel mounts. It comes in at $90, and serves as an interesting couterpoint to the liquid coolers that sell for around the same price. While we've never experienced any issues with reliability of liquid coolers, we know a lot of purists would prefer not to mix water with their precious high-end PCs, and for them, the NH-D15 can holds its own, as our tests will show.

Note that manufacturers were so excited about this AM4-focused review that we also received six additional air coolers, from Arctic, Cryorig, Noctua, Scythe (which sent two!), and SilverStone, and we'll be testing them in a separate article. Update: You can read that follow-up article right here!

Test Method

As always, we benchmark coolers on the latest test platforms, meaning you know how these coolers will work on gear you're buying today. Here's the system we used to rate our contenders:

With AMD's Ryzen platform taking the market by storm (we estimate that it now represents 20% of all CPU sales, up from close to zero at the beginning of 2017), we felt it was critical to show the platform some love by using it in this roundup. When Ryzen CPUs hit the market, one of the biggest problems was actually finding a cooler that would work with them. While most coolers still don't have the necessary AM4 brackets in the box, cooler manufacturers realize that all their new models must have them if they're going to become serious contenders for the next best seller.

A couple of other components deserve a bit of explanation. This being our AMD platform, we felt we had to include an AMD-based video card, but AMD's new Vega series is a complete flop in our opinion, so we turned to our trusty Sapphire Radeon Fury Nitro. No, you shouldn't buy it today (and in fact, you can't because it's been discontinued), but it's still a potent gaming weapon, easily beating out anything you can find for under $300 today (we picked ours up for $250 a year ago, which is a sign of how the mid-priced market has stalled!). And the other great thing about it is that it has a zero-fan mode, which was critical to our noise testing. During all of our CPU cooler testing, it remained completely and utterly silent.

Finally, we have our case of choice, the Thermaltake View 31 RGB. In addition to being quite a looker, this is the perfect platform for cooler testing. If there's one thing Thermaltake understands, it's how to design a case that can actually fit any cooler on the market. And this shouldn't be a surprise, given that Thermaltake markets more coolers than any other manufacturer in the world, including some very fancy custom loop solutions. We've grown pretty tired of other case manufacturers (including otherwise-excellent ones like SilverStone and Phanteks) marketing their mid-sized cases as having broad 240mm and 280mm cooler compatibility when they really don't. We love these cases, but not for liquid cooling. Thermaltake gets it right, and sure enough, we didn't encounter a single issue during any of our cooler testing with the View 31 - it was a perfect platform for this test.

To provide a true challenge to these high-powered coolers, we skipped stock testing all together, as our Ryzen 7 1700 runs at a leisurely 3.2GHz, with a rated TDP of just 65W. That's not nearly stressful enough to even bother with liquid cooling. We instead turned up the heat with an overclock of 3.8GHz, using 1.27V. We tried to dial in a 3.9GHz overclock with less than 1.35V (the reasonable limit to ensure CPU longevity), but couldn't get it stable. Note that a lot of reviewers boasted of Ryzen overclocks of 4GHz and even 4.1GHz, but they typically were using 1.45V to get there. You can kiss those CPUs goodbye in the long run.

In terms of cooler settings, most reviews simply run coolers at maximum RPM, show the results, and on a separate page might provide noise data. Frankly, this just isn't good enough. Performance data divorced from noise data is meaningless, and it has encouraged manufacturers to "juice" the benchmarks by shipping coolers with ever-faster fans and incredibly-noisy pumps. Therefore we ran our coolers using PWM and/or DC motherboard controls for both fans and pumps. This allowed them to ramp down at idle, and ramp up for a moderate and extreme loads. We used the motherboard's standard fan profile, except for one tweak: we leveled out the profile through 40°C to eliminate the constant changes in fan and pump speeds that otherwise occur (and annoy) during idle periods as the CPU fluctuates between 30°C and 40°C.

And what about the actual tests we performed? We used three different test scenarios to benchmark our coolers. First is idle at the desktop, where we report the minimum over a five-minute span (minor OS operations can spike temperatures momentarily, but these spikes can be ignored). Second is load in the CPU-z built-in benchmark, where we report the maximum after a 5-minute run. The third is Prime95 Small FFTs, where we report the maximum after a 10-minute run. As you'll see, each of the tests we ran illustrates a distinct facet of cooler performance, allowing us (and you) to gain a better understanding not just of how these coolers perform, but why they perform the way they do. Temperature data are collected using the wonderful app HWMonitor. All analysis was conducted with an ambient temperature of 69.5°F. Noise data was collected with a sound meter placed at the top of the case, a few inches from the radiator mount, and all other fans in the system were shut off, including the case fans and power supply fans.

All right, with that introduction out of the way, it's time to get into the nitty-gritty of our results, starting with a review of installation!